Purplish capillaries on the legs are usually caused by vasculitis, purpura, and capillary dilatation. 1. Vasculitis: Vasculitis may lead to purple capillaries on legs, which generally refers to the inflammatory reaction occurring in blood vessels, usually due to drug stimulation, bacterial infection, serum sickness, etc. It may cause weakness of the patient’s lower limbs, pimples, erythema and other symptoms. 2. Anaphylactic purpura: Anaphylactic purpura may lead to subcutaneous capillary dilatation, triggering purple capillaries on the legs, usually due to mosquito bites, food allergies, viral infections and other reasons, may cause patients with lower extremity skin purpura, joint pain, weakness and other symptoms. 3. capillary dilatation: capillary dilatation may cause capillaries to show up on the skin, resulting in purple capillaries on the legs, generally refers to skin diseases occurring in the trunk or face, usually due to mast cell hyperplasia, vascular blockage, venous pressure and other reasons, may cause patients with local redness, roughness and other symptoms. The purple capillaries on the legs may also be due to other diseases. It is recommended that the patient go to the hospital in time, complete the examination, clear diagnosis and reasonable treatment under the guidance of the doctor.